State Assemblyman Alec Brook-Krasny (R-Brooklyn) says someone working on behalf of fellow Republican Michael Ragusa forged his signature to get Ragusa on the primary ballot to rep his Brooklyn City Council district – and the enraged legislator has alerted the authorities.

“This is not my signature,” Brook-Krasny said in Wednesday letter to Brooklyn DA Eric Gonzalez obtained by The Post. “I trust that your office will take any appropriate action you deem fit.”

Brook-Krasny said Friday that he knew the snafu was not a case of a fellow Brooklynite having the same name as him — because the petition listed his address alongside the phony John Hancock.

“The situation is mind-boggling for me,” Brook-Krasny, who sits on the Assembly Election Law Committee, told The Post. “I’ve always fought for the total transparency of elections and in the process, and all of a sudden, someone just forged my signature.

“Just, it’s very upsetting,” he added.

Ragusa is running to be the Republican candidate to represent Council District 47, which includes parts of Coney Island and Gravesend.

He is facing incumbent Ari Kagan, who switched parties from Democratic to Republican last year.

Ragusa could not be reached for comment Friday afternoon, but he faces a similar accusation from state GOP Committee Member David Sepiashvili — who claimed that his signature was also forged on a ballot petition submitted on Ragusa’s behalf in a near-identical letter to Gonzalez

A rep for Gonzalez did not immediately respond to a request for comment.